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Filed under Quick Tips on December 7, 2007 by Javier Julio

ColdFusion Structures: Differences in Version 7 and 8

I know my fair share of ColdFusion bloggers that have started to dig "under the hood" and see what Java objects are being used by CF even utilizing undocumented Java methods in their CF code. I never thought I'd actually take the plunge myself but I had to uncover an issue with one of our application's moving from CF7 to CF8.

The code at fault has a very simple task: to make asynchronous HTTP calls to log incoming requests. Since the application was originally running on CF7 we needed a third party library to make asynchronous HTTP POST and GET requests so we brought in Mark Mandel's AsyncHTTP. The library provides a CFC (ColdFusion Component) that acts as a wrapper for a set of Java classes that both contain a post and get method.

After viewing some cfdump's I logged I noticed an error that read "The post method was not found". The post method in the CFC was firing but the error occurred when trying to call the post method in the AsyncHTTP Java object.

With another cfdump of the Java object itself I noticed a post method with no arguments and one with two (which happens to be the one we are using). The first argument is of type java.net.URL (the URL being requested) and the second is of type java.util.HashTable (a ColdFusion structure containing form data). The post method was being called and given two parameters but I wasn't so sure that the second parameter was right.

I haven't written any Java code since college but I did remember about it supporting different method signatures. I wasn't sure if Java treated a method call that received the required number of arguments but did not match the argument types required as if the method did not exist but apparently it does. In fact a method signature in Java also accounts for the order of parameters on top of that. Some pretty hardcore stuff.

The post method was without a doubt receiving its first parameter of type java.net.URL (since it was creating a Java object of that type and passing it) so I decided to investigate the second. With one of our development servers running CF7 I ran a simple script that dumped all of the Java super classes a ColdFusion structure has. I ran the same script on CF8 and the output did not match. In fact it has one parent less. You can see the results below:

ColdFusion 7

• coldfusion.runtime.Struct
• coldfusion.util.FastHashtable
• java.util.Hashtable
• java.util.Dictionary
• java.lang.Object

ColdFusion 8

• coldfusion.runtime.Struct
• coldfusion.util.FastHashtable
• coldfusion.util.CaseInsensitiveMap
• java.lang.Object

As you can see a structure in CF8 no longer has a parent class of java.util.HashTable and this leads to Java not being able to find the post method since it's looking for that type but is not getting it. After seeing these changes I wondered if this is one of the reasons too why structure creation in CF8 is considerably faster (much like everything in CF8!).

With this information in hand I rather stupidly email Mark notifying him of my discovery and if a fix to the AsyncHTTP library would be easy. Why stupid? Well CF8 right out of the box now allows us to make asynchronous HTTP requests simply using a combination of cfthread and cfhttp. Problem solved! Our application is now running in production and performing like a true champ thanks to CF8!

Unfortunately, this leads us to no longer use Mark's awesome AsyncHTTP library but I'm sure he will understand. CF7 and AsyncHTTP or CF8? Oh that's a tough one. Sarcasm aside, Mark thanks for the advice and providing such a great library to the community!

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